1. Field
Exemplary embodiments of the present invention relate to a nonvolatile memory device and a method for fabricating the same, and more particularly, to a nonvolatile memory device including an air gap formed between gate structures and a method for fabricating the same.
2. Description of the Related Art
A nonvolatile memory device maintains data stored therein even though power supply is cut off. For example, a NAND flash memory device and the like are widely used.
A conventional memory device includes a plurality of gate structures each having a tunnel insulating layer, a floating gate, an inter-gate dielectric layer, and a control gate which are sequentially stacked. Typically, the floating gate is formed of polysilicon doped with impurities.
However, while a subsequent process is performed after the gate structures are formed, the impurities of the floating gate may not be maintained. For example, the impurities of the floating gate may escape during a subsequent heat treatment, or impurities may be implanted into the floating gate during a subsequent ion implantation. As such, when the impurities of the floating gate are changed, memory cells may have non-uniform characteristics. In this case, a distribution difference between memory cells may increase.
Recently, as the distance between gate structures decreases with the increase in integration degree of nonvolatile memory devices, interference between memory cells has increased.